Personally i've found my little stumpy fingers aren't really long enough, and the angle you go in at makes it alot tougher! If possible try having your OH give it ago and guide them along with how you feel!
Make sure you are going nice and slow and arousing yourself beforehand so you're more relaxed and ready. Lube up your fingers (you can never have too much lube!) and try gentle pressing and exploring. Change it up a little and keep experimenting, try constant pressure inside your bum and remember that everybody's p-spots are in different places. Have you tried massaging around the area between your balls and anus? It's meant to feel amazing, I think it's called the perineum and it's very sensitive. Have you tried using a vibrator on this area? Stimulate your bum just by running the vibe around your inner thighs and between your cheeks but don't insert it, just get used to the sensations and massage yourself. Again, don't forget the lube! It's just as important during external stimulation as well as internal.
When you have experimented a bit more you may want to move onto internal bum fun :) You can use your fingers, and use scissoring motions to stretch yourself, but take it easy as your bum won't be used to it. Try wearing a small, soft butt plug during the day and use lots of anal lube. A beginner's plug like this is really good: http://www.lovehoney.co.uk/product.cfm?p=30575 and it's in the 2 for £15 offer as well! It will stretch you a little bit but you have already said you have tried toys and fingers before so I think a tiny one won't provide much stimulation. This one looks a bit bigger and may be more stimulating for you.
You could always try anal beads - http://www.lovehoney.co.uk/sex-toys/anal-sex-toys/anal-beads/ I have the LH beginner's ones, the pink-purple ones, and they are good for beginners. You could try inserting them and then pulling them out on the height of orgasm. Or there's always the good old fashioned wand vibrator - http://www.lovehoney.co.uk/product.cfm?p=31087 which is meant to be super-powerful and the vibrations travel through your bum to stimulate your p-spot. This wand is not for inserting!! You just use it externally to massage and arouse your p-spot. There are attachments though if you wanted to look into that!
Do not get disheartened if you can't find your p-spot, just keep perservering, but don't let it rule your life. You can still enjoy your sex life and try things like rimming, pegging and bum fun without finding your p-spot. Why not get your missus to give you a full body massage? It may turn you on more and you may discover new things! Take it easy and don't be too hard on yourself if you can't find that elusive spot, keep trying, and have fun! :)
I've been experimenting for a little while with a dildo and a probe (admittedly, at the same time, occasionally! ^^') and although most info states the p-spot to be around 2-3" inside the rectum, mine seems a little deeper. It may take a little while to find it and depending on your own physiology, might require a little pressure to know about it.
I can only go on my own experience, but my most comfortable position is on my side, in a semi-foetal position. Using a probe such as this:- http://www.lovehoney.co.uk/product.cfm?p=2041 or a dildo and plenty of lube, insert gently and angle the head towards your scrotum, the handle towards your spine and explore the region from just above your rectum, working deeper gradually, applying a little pressure, but not thrusting. Work in circles too, as your p-spot might not exactly be where the textbooks say it is. For me, the main sensation of finding it is an intense tingle from just behind the scrotum, more-or-less in line with the penis. Gently work the area and you may feel a slight, not uncomfortable pressure from behind your penis, deep inside the scrotum and clear precum should start flowing soon after. The quantities very, even with me, from a slight dribble to practically soaking the sheets.
With continued stimulation, the sensations can get very intense. In the six-or-so months I've been practicing solo bum fun, I've never orgasmed solely from p-spot stimulation, but the orgasms I've experienced while masturbating - having laid only back and gyrating my hips on the dildos - have been amongst the most intense - and messiest! - I've ever had.
Keep trying, have patience and believe me, you'll reap the rewards. And how!
I can find and milk mine with a finger it's about 2 1/2" so a full finger length in, a little pressure and a circular motion works for me, but I prefer a crystal dildo. I can apply more pressure and get a good flow.
If my partner wears her strapon with a shortish dildo and the right depth stroke she can get me flowing that way. It also leaves me to enjoy the sensations and mentaly drift. They say that the best sex is between the ears.
I have to say that mine's pretty tricky to reach... I need something very firm, directed pretty much straight upwards (when I'm lying on my back) - no way I could reach it with fingers!
Mh, I'm in the same boat there; I'm nowhere near limber enough to reach with my fingers and believe me, I've tried! I also need a fair amount of applied pressure to stimulate my prostate effectively.
I'm very fond of using my glass dildos for prostate play and, as much out of frustration than anything else, I developed a trick where I lie on my back, wrap the protruding end of the dildo in a towel, t-shirt or something of that order and pull the ends of the fabric up towards your back, lying on the material. It has the effect of pushing the head into the prostate region, where you can use hip movements to locate and stimulate it. I don't know if it would work for other toys, but it sure works well with my glass ones, which are also tough enough to handle that kind of motion. It also leaves your hands free to masturbate, or use other toys.
As I said on my previous post, I haven't had a singular p-spot orgasm (yet!), but it still gives a delicious intensity to 'regular' orgasms and given the scientific evidence suggesting that it might also reduce your chances of prostate cancer, it's win-win, really!